N-Heterocyclic Carbene-Au(I) Complexes Immobilized on Solid Supports

N-Heterocyclic carbene-Au(I) complexes immobilized on silica gel, ordered mesoporous silica (MCM-41), and delaminated zeolite (ITQ-2) were prepared and used as catalysts in the hydrogenation of alkenes. The reactions of N-heterocyclic carbene-Au(I) complex 1 bearing triethoxy­silyl group with silica gel, MCM-41, and ITQ-2 gave the corresponding solid-supported carbene-Au(I) complexes 2a-c (eq. 1). The hydrogenation of diethyl citraconate and diethyl benzylidenesuccinate took place in the presence of the carbene-Au(I) complexes 2 to give the hydrogenated products with high TOF (eqs. 2 and 3), where the ITQ-2-supported carbene-Au(I) complex 2c showed the highest catalytic activity. The carbene-Au(I) complex 2b was reused three times without significant loss of catalytic activity.